This invention is primarily directed to recreational vehicles and more particularly to motor homes or coaches. The invention will be described as it applies to motor home use but the reader will appreciate that it has application to similar types of circumstances where stabilization and/or leveling of a carrier body is desired.
In a motor home there are conflicting needs or desires. While the motor home is being driven, comfortability (as well as structure preservation) requires that the body be suspended from the vehicle axle in a manner whereby irregularities of the roadway as encountered by the motor home wheels and axles are not directly transmitted to the body but instead are absorbed in part by the suspension system, e.g., in the form of springs or cushions. The hard bumps of the wheels are thus transmitted as a soft bounce or rocking of the body.
However, when the motor home is parked, that same suspension system provides instability and as occupants move about in the body of the motor home, there is felt a rocking of the motor home which is undesirable. Also, whereas the motor home operator will seek to find a level spot on which to park the motor home, such is often not available and even in RV parks, the pads are sometimes slightly off level and it is desirable to level the motor home body.
A crude form of leveling is to simply drive the motor home up onto wooden blocks of different thicknesses. This provides the leveling function but not stabilization as the body is still supported on the suspension system. Such has been largely replaced with leveling jacks. A leveling jack is typically mounted to the body and positioned behind each of the wheel sets (two in front and two in back although three jacks, one centered in front between the front wheels and two behind the rear wheels are not uncommon) and typically a hydraulic system (but not necessarily hydraulic) is actuated to selectively lower the jack plungers (cylinder rods) to the ground and thereby in large part provide direct support from the body to the ground. Various degrees of sophistication in the controls for the jacks enable the motor home operator to vary the plunger extensions of the various jacks for leveling the body and in the process, because the body is now supported directly on the ground, the body is also largely stabilized.
Several factors will be apparent from this arrangement. Should the operator attempt to drive the motor home without first raising the jacks, the jacks will be damaged. If a jack malfunctions and will not raise into the travel position, the motor home cannot be moved. If the support pad on which the motor home rests is soft ground, the jack plungers will simply sink into the ground and support blocks placed under the jacks are required. As weight is shifted from the wheels to the jacks, the jack plungers can slip which can damage the jacks and/or create a safety concern.
Another known leveling system uses air bags for the suspension system and with the motor home parked, selective ones of the air bags are partially deflated to produce leveling but not stabilization as the springiness of the suspension system has not been avoided.